While there have been disagreements about exactly what to do about health care during the 2020 campaign, one thing we can say for sure is that if any Democrat becomes president next year, he or she will attempt to pass a sweeping, ambitious reform.

And if you want to get a sense of how dreadfully complex and difficult it’s going to be, just look at the escalating war between Sen. Bernie Sanders (I-Vt.) and the most important labor union in Nevada, where caucuses will be held next week.

The Culinary Workers Union (CWU), which represents 60,000 housekeepers, cooks, and other workers who staff the state’s casinos, has not made an endorsement this year. What it has done is distribute leaflets to its members that contain a strong criticism of Sanders (and to a lesser extent, Elizabeth Warren). The subject is the health insurance the union has secured for its members.

One leaflet, which synopsizes candidates’ positions on health care, says Sanders would “End Culinary Healthcare," a reference to the union’s much-envied insurance plan. Another that did not name Sanders but obviously referenced his support for Medicare-for-all criticized “candidates suggesting forcing millions of hard working people to give up their healthcare.”

That was only the beginning. Sanders’s army of passionate supporters then began laying into the CWU. And in response, the union released a statement saying:

It’s disappointing that Senator Sanders’ supporters have viciously attacked the Culinary Union and working families in Nevada simply because our union has provided facts on what certain healthcare proposals might do to take away the system of care we have built over 8 decades.

Meanwhile, Sanders himself is trying to reassure the union and workers generally that this disagreement shouldn’t obscure his long pro-labor record.

How does this look to opponents of health insurance reform? I just got a gleeful press release about this dust-up from the Partnership for America’s Health Care Future, a group funded by hospitals, doctors, insurance companies and drug companies whose goal is to crush not just Medicare-for-all but a public option as well.

It’s not as though the health care industry, which is desperate to stop any reform that might threaten its profits, is a natural ally of labor. But once the next Democratic president tries to pass health reform, the industry will be aggressively courting unions with “They’re gonna take away your health care!” messaging to try to drive a wedge through the pro-reform coalition.

We should be clear that opposition to Medicare-for-all is hardly universal in unions (here’s Sara Nelson, head of the flight attendants union, lambasting Pete Buttigieg for making essentially the same argument as the CWU). But what we have here is a complex interplay of interests and values.

Unions are very much built on principles of solidarity and common purpose, even with those who aren’t members. That’s the whole point of unions: They take your individual concerns about how you’re treated on the job and help you politicize them (in the best sense) by seeing them in a broader context and linking your fate with those of other people.

But in this case, that runs up against a very particular interest some union members have in holding on to what they’ve got. And this isn’t an unreasonable objection to Medicare-for-all: We fought hard for our good benefits and don’t want to give them up. It is indeed possible that if you have terrific insurance like CWU members do, in a single-payer system your benefits might not be quite as good (though Sanders’s version of single-payer is extraordinarily generous, with almost everything covered with zero cost-sharing).

We have no idea how this will affect the results in Nevada. Still, this is an excellent illustration of just how complicated health-care politics are. It’s an intricate puzzle of competing interests, alliances that can be torn apart, hundreds of billions of dollars at stake, and fears that aren’t too hard to activate.

But to listen to the candidates, it won’t be that difficult to navigate when it comes time to actually pass reform. Sanders says he’ll mobilize the movement he has built, which will be so powerful that it will bust through all opposition and force even Republicans to assent to Medicare-for-all. Buttigieg says that “Medicare for all who want it,” i.e., a public option, gives enough freedom and choice to everyone that it will be embraced as a sensible and non-threatening option.

They’re both wrong, but it’s hard to really blame them; no candidate is going to say, “Here’s what I support, but trying to pass it is going to be a nightmare and we’ll probably fail.” If a Democrat is elected, however, that will be the reality.

The Affordable Care Act — which was far less threatening to all those moneyed interests than even a public option is, and was considered when Democrats had strong majorities in both houses of Congress — was the most difficult piece of legislation to pass in decades. The next reform is going to be even harder.

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